Covered elastic yarn

ABSTRACT

The present invention relates to a covered elastic yarn with an elastic thread as a core yarn, and a continuous thermoplastic multifilament thread as a sheath yarn, wherein the respective filaments forming said covered elastic yarn are respectively tangled with each other to retain flux form, and at the same time to form the sheath-core system, and said sheath yarn wraps the outer periphery of said core yarn but is reversed irregularly and intermittently in said direction, and said sheath yarn and said core yarn are substantially twistless.

United States Patent [191 Tsujita et al. I

[ 1 Apr. 30, 1974 COVERED ELASTIC YARN Inventors: Yasuo Tsujita;Toshihiko Kimura,

both of Otsu; Shigeji Yamashita, Shiga-ken; Kazuo Yuki; Hiroshi Asami,both of Ot'su, all of Japan Assignee: Toray Industries, Inc., Tokyo,Japan Filed: Ma 17, 1971 Appl. N0.: 143,940

Foreign Application Priority Data May 18, 1970 Japan 45-41579 US. Cl.57/152, 57/157 TS, 57/163 Int. Cl D02g 3/32 Field of Search 57/34 HS,12, 152, 163, 57/157 TS References Cited UNITED STATES PATENTS 11/1966Rapuza 57/152 3,393,505 7/1968 Reid et a1. 57/152 3,447,296 6/1969Chidgey et al.... 57/34 HS 3,460,338 8/1969 Morrison 57/ 163 3,540,20411/1970 Tanaka et a]. 57/163 Primary Examiner.lohn Petrakes [57]ABSTRACT The present invention relates to a covered elastic yarn with anelastic thread as a core yarn, and a continuous thermoplasticmultifilament thread as a sheath yarn, wherein the respective filamentsforming said covered elastic yam are respectively tangled with eachother to retain flux form, and at the same time to form the sheath-coresystem, and said sheath yarn wraps the outer periphery of said core yarnbut is reversed irregularly and intermittently in said direction, andsaid sheath yarn and said core yarn are substantially twistless.

6 Claims, 15 Drawing Figures mmmmsomm 3.807162 SHEEI 1 (1F 3 PRIOR ARTFig. I

PRIOR ART Fig.2

lNV EN TORS YASUO TSUJITA, TOSHIHIKO KIMURA, SHIGEJI YAMASHITA,

KAZUO YUKI 0nd HIROSHI ASAMI ATTORNEYS.

PATENTEDAPR 30 m4 SHEET 2 OF 3 [NVENTORS YASUO TSUJITA, TOSHIHIKOKIMURA, SHKSEJI YAMA KAZUO YUKI and HIROSHI ASAMI SH ITA ATTORNEYS.

rmmzmmu m4 SHEET 3 0F 3 INVENTORS. YASUO TSUJITA,TOSHIHIKO KIMURA,SHIGEJI YAMASHITA, KAZUO YUKl 0nd HIROSHI ASAMI ATTORNEYS.

1 COVERED ELASTIC YARN BACKGROUND OF THE lNVENTlON:

This invention relates to a novel elastic yarn and to a method of makingthis yarn.

The yarn according to this invention is a covered yarn wherein amulti-filament, continuous filament thread as a sheath yarn wraps a coreyarn in such a manner that said multi-filament thread wraps round saidelastic thread, and said core yarn and said sheath yarn aresubstantially twistless.

In conventional covered elastic yarns which are generally used atpresent core spun yarn or rubber yarn or polyurethane elastic fiber yarnis used as the elastic core yarn and other filament yarn or spun yarn istwisted around said cores, or said yarns are associated and twistedthereon.

In addition, elastic yarn such as rubber yarn or polyurethane elasticfilament yarn is used as the core in the convection of ejected fluid,and other filament yarns are tangled therewith, or elastic yarn andthermoplastic filament yarn are associated, and the associated yarns arecrimped in twisting-heat setting-untwisting type method so calledltallian type" (twister) to produce over-untwisting yarn, While, theconventional covered elastic yarns have excellent characteristics, theyhave the following drawbacks.

First of all, in the case of single or double covered yarn preparedeither in such a manner that non-elastic yarn wound on a bobbin mountedon a rotating hollow spindle is wound onto the rubber or polyurethaneelastic core filament as that filament is drawn through the spindle,'orin another case of single covered yarn prepared in such a manner thatnon-elastic sheath yarn and rubber or polyurethane elastic core filamentyarn are twisted under tension in a ring twister, considerably excellentcovering property can be obtained but it is necessary to carry outappropriate thermal setting for power down and the setting of twistingtorque because of the high torque attributable to the twistingoperation. Other problems include excessive stretch power, and, inaddition, there is a limitation to the speed spindle; in theexperimental calculation of the productivity of fine yarn (total denier90 denier), there is no such a case that the processing speed should gobeyond m/min even when the number of revolutions of the spindle isadjusted to be 10,000 rpm, and the number of twists is adjusted to be500 turns/m.

On the other hand, in addition to the above given drawbacks, there is adrawback that crimped yarn such as wooly yarn to be used as coveringyarn must be separately prepared.

In addition, in the case of the conventional sheathcore type bulkedelastic yarn prepared in such a manner that polyurethane elasticfilament yarn and other filament yarn are passed through ejected fluidconvection, wherein the other filaments are disturbed around saidpolyurethane elastic filament yarn to be tangled the, covering yarn isnot twisted, and therefore the tangling property thereof is poor, andnot satisfactory, and there is a fear that the core yarn may be exposed,and at the same time the cost of air is expensive. In addition to thesedrawbacks, as above, this process has a remarkable over-all drawback inthe cost of labor attributable to the complicated processes, and thecost of processing is therefore high.

On the other hand, in the case of over twisted yarn produced from theassociated elastic yarns and thermoplastic filament yarns by using theItalian type twister, the covering property is excellent but in view ofthe ordinary twisting process which is required in this case, theproductivity thereof is-not more than that of single covered yarn; atthe same time, the number of processes is increased, and the cost ofproduction is high, and therefore over-twisted yarn produced by theItalian type twister is not practical.

Thus, there is no twistless covered elastic yarn although there arethose conventional covered elastic yarns having actual twists, or poortangling property caused by fluidal convection.

it is a principal object of this invention to remove the above mentioneddrawbacks of the prior arts, and to provide a novel covered elastic yarnhaving fast elasticity and remarkably excellent covering property.

It is another object of this invention to provide a method for producingthe above mentioned novel convered elastic yarn.

in order to attain the above described objects of this invention,. thepresent invention has the following structure.

This invention relates to a covered elastic yarn comprising an elasticthread as a core yarn and a multifilament continuous filament thread asa sheath yarn, wherein the respective filaments forming said coveredelastic yarn are tangled to retain the fluxability and at the same timeto form sheath-core stage, and said sheath yarn wraps the outerperiphery of said core yarn, and is reversed intermittently andirregularly in said direction, and said sheath yarn and said core yarnare substantially twistless.

The present invention is explained more in detail in the followingparagraphs;

The yarn of this invention is produced by using elastic thread havingremarkably high elongation and recovery, such as rubber yarn orpolyurethane filament yarn, as the core yarn. Said core yarn may be amonofilament but it is preferable to use a plural number of associatedfilaments, i.e., multi-filament; as a matter of course it is mostpreferable that the number of filaments should be great.

The reason for this is that the tangling property of core yarn againstsheath yarn increases as the number of filaments in the core yarnincreases.

On the other hand, as the above mentioned elastic yarn, crimped yarn orsuch elastic yarn having shrinkability attained by chemicals can beused.

On the other hand, as said sheath yarn, a crimped yarn composed ofmulti-filament yarn composed of thermoplastic filaments can be used.

Said sheath yarn covers and is twisted around said core yarn, and thecore yarn is placed almost in the centre of said covering elastic yarn,and in regard to the direction of twisting of said sheath yarn, saidsheath yarn is twisted in such a direction that said sheath yarn istwisted with random interval and intermittently in the lengthwisedirection of said covered elastic yarn, and either filaments themselvesforming said sheath or the filaments forming said sheath yarn and saidcore yarn are mutually tangled to retain fluxability.

Sometimes, it is possible to partially melt the filaments forming s'aidsheath-yarn in order to improve the fluxability further.

When thermoplastic synthetic yarn is used as the core yarn, randomuntwisting or slight crimping can be observed intermittently in the samemanner as in the case of said sheath yarn.

In such a structure as described above, it is possible for said sheathyarn to be more excellently tangled against said core yarn.

For a better understanding of the nature of this invention, referenceshould be had to the following detailed description of specificembodiments thereof, when read in conjunction with the accompanyingdrawings forming a part thereof, wherein;

FIG. 1 (A) is a model schematic view of a length of conventional coveredelastic yarn, in its fully, or nearly fully, elongated condition.

FIG. I (B) is a model schematic view of a length of the yarn of FIG. 1(A) contracted further than in FIG. I (A).

FIG. 2 (A) is a model schematic view of a length of covered elastic yarnprepared by conventional falsetwisting method, in its fully, or nearlyfully elongated condition. FIG. 2 (B) is a model schematic view of alength of the yarn of FIG. 2 (A) contracted further than in FIG. 2 (A).

FIG. 2 (C) is a model schematic view of a length of the yarn of FIG. 2(B) further twisted.

FIG. 3 (A) is a model schematic view of a length of the yarn inaccordance with this invention, in its fully, or nearly fully elongatedcondition.

FIG. 3 (B) is a model schematic view of a length of the yarn of FIG. 3(A) contracted further than in FIG. 3 (A).

FIG. 4 (A) is an enlarged cross sectional view of the yarn of FIG. 2(A);

FIG. 4 (B) is an enlarged cross sectional view of the yarn of FIG. 2(B); I

FIG. 5 (A) is an enlarged cross sectional view of the yarn of FIG. 3(A);

FIG. 5 (B) is an enlarged cross sectional view of the yarn of FIG. 3(B).

FIG. 6 (A) is a schematic view of false-twisting apparatus which, shownpartially in cross section, which can be used to make the yarn inaccordance with the present invention.

FIG. 6 (B) is a vertical sectional view of a guide in the apparatusshown in FIG. 6 (B). I

FIG. 7 (A) is a schematic view, partially in cross section, of modifiedfalse twisting apparatus which can be used to make the yarn inaccordance with this invention.

FIG. 7 (B) is a vertical sectional view of a star-wheel type pulleyusable for FIG. 8 (A).

Referring first to FIG. 1 (A), FIG. 1 (A) is a model schematic view ofthe covered elastic yarn twisting two yarns (2) and (21) on the coreyarn (l) by a conventional spinning machine or a conventional twister,in elongated state. FIG. 1- (B) is a model schematic view of the coveredelastic yarn of FIG. 1 (A) contracted by 30 percent.

As is apparent from FIG. 1 (A), the filaments of the sheath yarns (2),(2') of the covered yarn are regularly twisted and therefore thecovering property of the covered elastic is remarkably excellent, butsince the filaments composing the covered yarns (2), (2') are controlledby twisting, the space occupied by said filaments becomes narrower, andthe bulkiness thereofis deteriorated, and this is accounted to be adrawback.

FIG. 2 (A) is a model schematic view of a covered yarn under tensionprepared by simply associating and conventional false-twisting the coreyarn (1) and the covering yarns (2), (2') and FIG. 2 (B) shows a modelschematic view of the same yarn shown in FIG.'2- (A) contracted by 30percent.

As is apparent from FIG. 2 (8), the core yarn (I) and the covering yarns(2), (2) have no twist at all, and it is very bulky but there is nocontact of the filaments composing the core yarn and the covering yarn(See FIG. 4 described below).

Therefore, the covering property is very poor, and the core yarn and thecovering yarn can be separated by a slight external effect when thecovered yarn passes through a guide or tensioner, and the separated coreyarn and the covering yarn are not restored to their original state, andthis is accounted to be a serious drawback.

Therefore additional twisting is required after the false twisting orpre-twisting is required before the twisting.

FIG. 2 (C) shows the form of the yarn after the above mentionedadditional twisting or pre-twisting. Theincrease of the number ofprocesses in making this yarn, and its poor bulkiness are accounted tobe drawbacks.

FIG. 3 (A) and FIG. 3 (B) show the covered elastic yarns obtained inaccordance with the present invention in comparison with the coveredelastic yarns obtained in accordance with the prior arts.

FIG. 3 (A) shows the covered elastic yarn of the present invention undertension in the same manner as in FIG. 1 (A) and FIG. 2 (A), and FIG. 3(B) shows said yarn contracted by about 30 percent.

FIG. 3 (B) is a model schematic view of the structure which makes use ofthe merits of the yarns of FIG. 2 (B) and FIG. 1 (B), so as tocompensate for the respective drawbacks thereof.

In other words in the yarn structure of FIG. 3 (B), the filamentscomposing the sheath yarn (2), (2) covering the core yarn (l), arereversed in the twisting direction at random intervals.

Point (a) of FIG. 3 (A) and FIG. 3 (B) shows the twist reversing pointof said filaments.

The above described phenomena are demonstrated by all of the filamentsforming the sheath yarn, and therefore the covered elastic yarn as awhole has remarkably excellent covering property, and at the same time,the filaments forming thesheath yarn have almost no contact against thecore filaments attributable to twisting because the filaments formingthe core yarn and sheath yarn are substantially twistle'ss, andtherefore excellent bulkiness can be attained.

In addition, a covered elastic yarn of FIG. 2 (A), (B), produced inaccordance with a conventional falsetwisting method is covered with thecovering yarn not being closely adhered on the elastic yarn (l) as isapparent from FIG. 4 (A), (B), while in a covered elastic yarn producedin acccordance with the present invention, as is apparent from FIG. 5(A), (B), the thermoplastic continuous multifilament thread is partiallylaid in the elastic thread (1) in such a manner that the thermoplasticcontinuous multifilament thread is inserted into said elastic thread.

Therefore, the yarn of the present invention has remarkably excellentfluxability, and the slipping-off of the core yarn (l) is less againsttension and pulling, and the covering property is not at alldeteriorated.

Namely, in accordance with this invention, an elastic thread is releasedfrom the package thereof under tension, and a thermoplastic continuousmulti-filarnent thread and said elastic thread are associated, and thusassociated, the thermoplastic continuous multifilament and the elasticthread are passed through the fluxing guide, and are arranged in such amanner that said elastic thread can become the core and that saidmulti-filament thread can wrap said elastic thread, and the thusobtained fluxed and associated yarns are then supplied into a falsetwisting machine, to carry out a twisting, heat setting and untwistingprocess.

The method of the present invention is explained in more detail in thefollowing paragraphs.

In supplying elastic thread and thermoplastic multifilament threadsimultaneously to the same false twisting machine, the relation of saidelastic thread and thermoplastic multi-filament thead is such that thefilaments of said thermoplastic multifilament thread are arranged insuch a manner that the elastic thread can.

be wrapped by said filaments, and the covered elastic yarn thus obtainedhas elastic thread within the fiber flux of the crimped thermoplasticmulti-filaments by means of false twisting, and the elastic thread iscovered with the crimped multi-filament, and therefore the two cannot beeasily separated.

Moreover, in regard to the covered elastic yarn thus obtained, theelastic thread as the core yarn and the filaments forming the sheathyarn are substantially untwisted, and the generation of torque and kinkcan be hardly observed.

In regard to the determination of the temperature at which the falsetwisting is carried out in accordance with the present invention, it isa matter of course that temperature should be adjusted to be sufficientto fix the desirable crimping of the thermoplastic multifilament to beused as the sheath thread, but it is necessary that the kind of elasticthread used as the core yarn should be taken into consideration.

For example, when an elastic thread which is subject to thermaldeterioration (such as natural rubber) is used, the temperature at whichfalse twisting is carried out must be adjusted to be low so as notto-damage the elastic thread, or said elastic thread must be protectedby the sheath thread, and therefore it is a matter of course that theconditions such as the kind of the sheath thread, temperature and thenumber of twisting turns should be taken into consideration.

On the other hand, when a thermoplastic elastic thread, such aspolyurethane fibers, is used as the core yarn and the elastic thread issupplied under a high tension or high elongation in a high temperaturezone, the elongation of the covered elastic yarn product is less; on thecontrary, when the elastic thread is supplied under less tension or atlow elongation, the elongation of the covered elastic yarn product islarger.

Conversely, when the elastic thread is supplied under a high tension orat high elongation, in a low temperature zone, the elongation of thecovered elastic yarn becomes larger while if the elastic thread issupplied under a low tension or at low elongation, the elongation of thecovered elastic yarn product becomes small. Therefore, in accordancewith the method of the present invention, it is possible to select thetension of the core yarn elastic thread and the temperature at whichfalse twisting is carried out to meet the object of this invention.

Furthermore, it is possible to select the temperature at which falsetwisting is carried out in such a manner that the fibers forming thesheath strand can be partially melted and adhered to each other.

In addition, when polyurethane elastic yarn, as the core yarn, issubjected to the false twisting treatment at a temperature in theneighbourhood of the melting point of the core yarn, i.e. if theheat-setting of the false twisting is carried out at a temperatureranging from lC to 200C, or more preferably at C, the polyurethaneelastic yarn is softened, and, in addition, the twists attributable tothe false twisting is generated on the surface of said polyurethaneelastic yarn, and therefore the fibers forming said sheath strand arelaid into the concave portions produced by the twisting of said elasticyarn.

Therefore, the covering property of the covered elastic yarn which canbe obtained as described above, can be further improved, and at the sametime the migration of said sheath thread cannot be brought about by theexternal frictional force.

What is important in the method of the present invention is that insupplying the elastic thread as the core yarn and the thermoplasticmulti-filaments thread as the sheath yarn to the same false twistingmachine, the filaments forming the thermoplastic multi-filaments shouldbe parallelly arranged in such a manner as to rap the core yarn.

The above mentioned arrangement determines the superiority of thecovering property of the covered elastic yarn of this invention.

In order to arrange the respective filaments to be supplied to the falsetwisting zone, it is necessary that the relation of the respectivethreads, at the time when they are supplied, be sufficiently taken intoconsideration.

First of all, in order to place the elastic thread in the center, saidelastic thread should be supplied under tension, to prevent the freeslipping-off thereof, and furthermore the multi-filament thread shouldbe supplied under low tension to wrap said elastic thread.

When the respective threads are supplied in such a manner as describedabove, the fibers which are to become sheath form the outer side, and'the elastic thread which is to become the core thread is placed in thecenter.

In the above described embodiment, it is necessary to have a gude forfluxing the thread, i.e. a U or V shaped yarn guide or a star-wheel typepulley guide having a U or V shaped concave portion on the peripherythereof to arrange the filaments in the neighbourhood of thetwist-starting point, and to prevent, from that point backward thetwisting of the fluxed threads which abruptly starts, beyond that point,using a nip roller guide to define that point.

In other words, in the present invention, the elastic thread andnon-elastic thread are directly introduced into a false twisting machineafter they have been associated, but it is necessary to keep saidelastic thread and non-elastic thread in the associated state for apredetermined time, and said elastic thread is introduced into thecenter of said non-elastic thread by the above mentioned treatment.

Therefore, a U or V shaped guide is preferable.

In other words, in accordance with the present invention, said core yarnand said sheath yarn are doubled,

and thereafter, the doubling state is retained for a predetermineddistance, while a tension difference is maintained therebetween in ayarn introducing zone of a false-twisting aparatus, in which the yarn isfalsetwisted while the backward travel of twist is controlled, andthereby said core yarn is sufficiently placed into said sheath yarn.

FIG. 6 and FIG. 7 are diagrams showing the embodiments of apparatus forcarrying out the process and for making the product of the presentinvention.

In FIG. 6 (A), the elastic thread which is positively released from thepackage (3) thereof by the roller (4), is supplied to a pair of feedrollers (6) of the false-twisting machine while being subjected totension.

On the other hand, the thread (8) which is released from package (7) ofthe thermoplastic multi-filament yarn which becomes the sheath yarnpasses through the guide (9), and is supplied to the feed roller (6) ofthe false-twisting machine, and is associated with the elastic thread(5).

The elastic thread (5) supplied by the feed rollers (6), and thecontinuous multi-filament thread (8) are arranged by the grooved guide(10) having a V shaped groove in the lateral cross section perpendicularto the running direction of said threads (5) and (8) in such a mannerthat said thread (5) is arranged within the central portion of saidcontinuous multi-filament thread (8). Said elastic thread (5) andcontinuous multifilament thread (8) are then subjected to false twistingby means of the false twisting spindle (l3), and the twisted portionthereof is thermally set by means of the heater (12), and when saidthreads have passed through said spindle (13), they are untwisted, andare drawn out by a pair of delivery rollers (14), and said threads passthrough the guide (15), and are taken up i into a package (17) by meansof a take up device such as drum type winder.

In other words, the false twisting is perfectly stopped by a nip roller(11), and the two threads keep their associated state between the feedroller (6) and nip roller (11). This prevents twist from travellingbackward to grooved guide (10) or said feed rollers (6) so that thestate of core-sheath of the two threads is not destroyed thereby.

FIG. 6 (B) is a diagram showing the cross sectional form of. groovedguide (10) in the plane perpendicular to the running direction of thethreads (5), (8), and

said elastic thread (5) is arranged into the central portion of saidcontinuous multi-filament thread (8) in said groove.

On the other hand, FIG. 7 is a diagram showing a modified form of theapparatus of FIG. 6 (A), (B). In FIG. 7 (A), the elastic thread (5)released by the positive feed-roller (4) from the package (3) thereof iselongated by a predetermined degree between said feed roller (4) anddelivery roller (14).

Said elastic thread (.5) is associated with the thermoplasticmulti-filament thread (8) released from the package (7) thereof in analmost tensionless state, and is supplied into the star-wheel typepulley (18).

FIG. 7 (B) is a cross sectional view of said star-wheel pulley acrossthe center of said star-wheel type pulley, Said star-wheel type pulleyis light and is rotated in the running direction of the threads (5), (8)on shaft (20) by contacting with the threads.

The peripheral portion (21) of said pulley (as seen in FIG. 7 (B)) has ashaped groove that helps said two threads take on a sheath-core formwithout adding high tension to said continuous multi-filament threadwhich becomes sheath thread by using said pulley and said elastic thread(5) arranged in the central portion of said continuous multi-filamentthread (8) therein.

Further, in FIG. 6 (A), a pin nip rollers (11) is provided in order toprevent the travelling of the twist of the false-twisting machine duringthe false twisting process, but when a pair of the nip rollers (11) isused, there is a fear that the sheath-core arrangement of the threads(5), (8) attained by the groove guide (10), may be upset thereby.

On the other hand, the star wheel type pulley as is shown in FIG. 7 (A)is rotated along with the running of the threads (5), (8), and thereforeit is not necessary to use such a pair of nip rollers (11) as is shownin FIG.

6 (A) because there is no fear that the twist of the false twistingmachine may arrive at the entrance portion of the groove (21) of saidpulley (l8), and only the guide (19) for converting the runningdirection suffices.

As described so far in the foregoing paragraphs, the respective threads(5), (8) associated in the sheathcore state, are taken up on the package(17) after they are subjected to the process fortwising-heatsettinguntwisting.

The covered elastic yarn thus obtained is an elastic yarn havingremarkably strong covering property, and the covering cannot bedestroyed even if it is used over and over again, and partial exposureof the core yarn thereof can be hardly observed, and the cover elasticyarn has a very uniform shape in the lengthwise direction thereof.

In addition, when the thermoplastic filaments are slightly melted andadhered by raising the temperature of the heater of the false twistingmachine, it is needless to mention here that faster covering can beattained and the covering becomes more compact.

The covered elastic yarn of the present invention has almost the sameprocessiability as the ordinary crimped yarns, and it is possible toadjust the crimping degree by adjusting the temperature of the heater ofthe falsetwisting machine and the stretch power thereof is almost thesame as that of the thermally set single covered yarn, or core spunyarn.

Since the covered elastic yarn of the present invention is twistlessyarn, snarls and kinks are not easily formed in the yarn of thisinvention when compared with the conventional single covered yarn to saynothing of the conventional false twisted crimped yarn.

Thus, the hank reeling property, hank dyeing property, hank windingproperty, cone-up property, preparing property for weaving, andpreparing property for knitting of the covered elastic yarn of thepresent invention are the same as or more excellent than those of theconventional false twisted crimped yarn or single covered yarns.

The woven or knit fabrics obtained from the covered elastic yarn of thepresent invention can present the soft touch of wooly yarn by crimpingprocess of the thermoplastic filaments and twistless covering processinto the elastic filament yarn attained thereby, without beingcontrolled by twist thereof, and has a special appearance as woven orknit goods.

The covered elastic yarn of the present invention can be directly usedfor producing the ordinary knit goods,

longitudinally stretchable woven fabric and, laterally stretchable wovenfabric, without employing any heat setting process or twisting process,and this is accounted to be an advantage of the present invention.

In particular, in the ease of the longitudinally stretchable wovenfabric, it is possible to omit sizing process by using the coveredelastic yarn prepared by slightly melting and adhering the thermoplasticfilaments at the time when false twistin is carried out.

When the covered elastic yarn of the present invention is used for knitgoods, there is a remarkable advan tage that the yarn having the samestretch power as that of the conventional thermoplastic yarn can bedirectly woven from the cheese of the false-twisted yarns since inaccordance with the prior art, the covered elastic yarn is used bythermally setting the same in most cases.

In addition, the processing speed of the covered elastic yarn of thepresent invention isfrom to 10 times the speed of the conventionalyarns, and it is apparent that the present invention can greatly'reducethe cost of production.

On the other hand, the method of this invention can be easily worked outdirectly on the conventional false twisting machine, or by a simpleimprovement of the conventional devices, and the operation required forworking out the method of thisinvention is hardly different from that ofthe conventional methods.

The following are the examples to further illustrate the presentinvention.

The method for measuring the elongation and covering property, andcoefficient of feeding asdescribed in the following examples of thepresent invention are explained below;

I. METHOD FOR MEASURING ELONGATION The yarn of the present invention waswound on the periphery of a 50 cm frame for 10 times, and thermaltreatment was carried out with 60C hot water for 30 minutes.

After having dried the yarn for 24 hours, 40 g a weight of par a yarnwas suspended thereon for 30 seconds, and the length I was read.Thereafter, the load was removed, and the yarn was left out to be shrunkfor 20 seconds, and then a weight of 0.16 g par a yarn was suspendedthereon for 30 seconds, and the length I, was read.

Elongation =1, -l,/l, X I00 10 zqmsrnoo FOR MEASURING THE COVERINGPROPERTY A weight of 40 g was suspended on the yarn of the presentinvention for 30 seconds, and the length of cm was marked on the yarn,and thereafter the weight was removed, and then the yarn was left out tobe shrunk for I20 seconds, and then, a weight of 0.5 g was suspendedthereon so to separate the core yarn and the sheath yarn thereof.

The length l, of the yarn with the weight hanging down is read.

Covering property 50 [J50 X I00 3. DETERMINATION AND COEFFICIENT OFFEEDING Coefficient of Feeding (Peripheral speed of feed rollerPeripheral speed of delivery roller/Peripheral speed of delivery roller)X 100 4. DEFINITION OF POLYURETHANE ELASTIC THREAD USED IN RESPECTIVEEXAMPLES A polyurethane elastic thread 40 denier-I filament used in thefollowing examples and comparative examples is a monofilament in whichsix polyurethane elastic filaments are coalesced, and a polyurethaneelastic thread denier-I filament is a monofilament in which 18polyurethane elastic filaments are coalesced.

EXAMPLES I, 2, AND 3,

1. Examples l and 2 A polyurethane elastic thread 40 denier-l filamentelongated by 3.5 times of the original length thereof and Nylon-6, 70denier-34 filaments being tensioned by 0.1 g were associated with eachother, and thereafter the associated filaments were supplied'into theapparatus embodiment as shown in FIG. 6. (A), (B), and treated underconditions as shown in items EX-l and Ex-2 of Table-1.

The resultsas shown in items EX-l and EY-Q ofTable-2 were obtained.

2. Examples 3 On the other hand, a polyurethane elastic thread 40denier-1 filament elongated 2.8 times the original length thereof andNylon-6, 70 denier-34 filaments being tensioned by 1.0g were associatedwith each other, and thereafter the associated filaments were suppliedinto the apparatus embodiment as shown in FIG. 6. (A), (B) and treatedunder conditions as shown in item EX-3 of Table-l.

The results as shown in item Ex-3 of Table-2 were obtained.

TABLE 1 EX-1 EX-Z EX-3 Materials:

Polyurethane thread (denier-filament) 40- 1 40-1 40- I Nylon-6 multifilament (denier-filament) 70-34 70-34 70-34 Conditions of processing:

Elongating degree of elastic thread (times) 3.5 3.5 2.8 Doubling tensionof Nylon-6 multi-filament (g)... 0.l 0.1 1.0 Existence of a groovedguide Yes Yes Yes Coefficient of feeding of processing (percent) 1 2 INumber of rotations of false-twisting spindle (r.p.m)..... 20 X 10* 20 X10 20 X 10 Number of false-twisting (turns/meter) 3600 3600 3600Temperature of heater (C) I I80 Length of heater (mm)......... 900 900900 Tension of twisting (g) 7 7 7 Tension of untwisting (g) l4 I6 20Number of true twist (turns/meter) 0 0 0 3: Considerations As isapparent from EX-l and EX-2 of Table-2, the

*Cl value: It is based on the rule ofJlS.

covered elastic yarns of the present invention, in the production ofwhich there is a relatively large difference between the tension of thepolyurethane elastic thread and that of the Nylon-6 multifilament, andheat-setting of the false-twisting is carried out at a temperatureranging from 180C to.

200C, have excellent covering property, because the respective filamentsof Nylon-6 are adhered to the outer surface of the polyurethane elasticthread.

On the other hand, the covered elastic yarn in accordance withExample-3, produced with only slight differential tension between thepolyurethane elastic thread and the Nylon-6 multi-filament and withheat-setting of the false-twisting at a temperature lower than 180 "C,i.e., [70C, has poor covering property, because the respective filamentsof Nylon-6 are generally not adhered to the outer surface TABLE 2 EX-1EX-2 EX-3 Number of filaments of Nylon-6z Multi-filament adheredto-polyurethane elastic thread (number/an optional cross section of thecovered elastic yarn) 22 16 Multi-filament not adhered to polyurethaneelastic thread (number! an optional cross section of the covered elasticyarn) l2 18 34 Covering property (percent):

Weight of 0.5g... 97 87 12 E ght Qfl-Ofi "he. ,2 94 80 0 Clz Coefficientof cry of el y (percent). 54 58 60 Coefficient of elongation(percent)... I79 I91) I)! Index of torque ,L l 8 Existence of thetwisting mass produced by rubbing motion Yes Yes Ycs 6f the polyurethaneelastic thread.

EXAMPLES 4 AND 1. Example 4 A polyurethane elastic thread denier-1filament elongated by 3.6 times the original length thereof and Nylon-6,denier-24 filaments, under 0.2

grams tension, were. associatedwith each other,

and thereafter the associated filaments were sup- TABLE 3 EX-4 EX-SMaterials:

Polyurethane thread (denier-filament) 40-] 40-] Nylon-6 multi filament(denier-filament) 70-24 70-24 Conditions of processing:

An elongating degree of elastic thread (times)..... 3.6 I 3.6 Doublingtension of Nylon-6 multi-filament (g) 0.2 0.2 Ratio of tension betweenan entry and an exit of the star-wheel type grooved guide L06 Existenceof a grooved guide Yes Yes Coefiicient of feeding of processing(percent)... 1 Number of rotations of false-twisting spindle (rpm). 20 X10 20 X 10 Number of false-twisting (turns/meter) 3.300 3,300Temperature of heater (C).... Length of heater (mm) 900 900 Tension oftwisting (5).. l2 1 I Tension of untwistint; (g) 22 20 Number of truetwist (turns/meter) 0 0 TABLE 4 EX-4 EX-5 A number of filaments ofNylon-6:

Multi-t'ilament adhered to polyurethane elastic thread (number/anoptional cross section of the covered elastic yarn) 14 i0 Multi-filamentnot adhered to polyurethane elastic thread (number/an optional crosssection of the covered elastic yarn) 10 I4 Covering property (percent):

Weight of 0.5g 1 00 98 Weight of 2.0g 99 96 Cl:* Coefficient of recoveryof elasticity (percent).. 57 58 Coefficient of elongation (percent) 14715] Index of torque 9 8.2 Existence of the twisting mass produced byrubbing motion None None 7 *CI value: It is based on the rule ofJlS.

3. Considerations 7 As is apparent from items of EX-4 and EX-5 ofTable-4, the covered elastic yarn of the present invention can beobtained by either apparatus emboditween said polyurethane elasticthread and Nylon-6 multi-filament thread, when a weight of 0.5 g wassuspended thereon.

As is apparent from the foregoing description, in the ment as shown inFIG. 6 or as shown in FIG. 7. But 5 present invention, the method inaccordance with Exthe coveringproperty of the covered elastic yarn ofample-4 is more excellent than that in accordance with Example 4,produced with the apparatus embodi- Example-5. ment of FIG. 7 which isprovided with a star-wheel TABLE 5 type guide, IS more excellent thanthat of the covered elastic yarn of Example 5 produced with the iExamples x apparatus embodiment of FIG. 6 which is provided 2:232: 1 Ewith a simple grooved guide. x. o.; cm 0 cm In both examples mentioned,it may seem as if there i? 3'3 3"; a is only a slight difference betweenthe covering propx, 0 cm 0.3 cm erty of Example-4 and Example-5, butactually there is 5 cm 0 X 0.54 cm 1.98 cm a five fold difference In themean value of the length m 4mm, differential used in calculatingcovering property cove-fins l00= 9.0 48.0/50.0 100= 96.0 defined hereinrim to the descri tion of Exam le 1 Empeny p p p X: arithmetical meanvalue As a matter of fact, m the covered elastic yarn produced inaccordance with Example-4, as shown in Table-S, all of the five samplesshowed little tendency to permit slipping-off between said polyurethaneelastic EXAMPLES 6 AND 7 thread and Nylon-6 multi-filament thread, whena A polyurethane elastic thread denier-l filament weight of 0.5g wassuspended thereon. and Nylon-6, 70 denier-24 filaments were treated Onthe other hand, in the covered elastic yarn pro- 25 under conditions asshown in items EX-6 and EX-7 of duced in accordance with Example-5, asshown in Ta- Table-6 with the apparatus embodiment as shown in ble-S,one of five samples showed about 20% (about FIG. 7, and thereby theeffects as shown in items EX-6 9.4 cm) of slipping of par length of cmthereof beand EX-7 of Table-8. were obtained.

M HTAEIE E EX-6 EX-7 Materials:

Polyurethane thread (denier-filament) 40-1 40-1 Nylon-6 multi filament(denier-filament) -24 70-24 Conditions of processing:

Elongating degree of elastic thread (times) Doubling tension of N ylon-6multi-filament (g) 3.6 2.2 Ratio of tension between entry and exit ofthe star-wheel type grooved guide. 1.08 I .95 Existence of a groovedguide Yes Yes Coefficient of feeding if processing (percent)......Number of rotations of false-twisting spindle (r.p.m.). 20X 10 20X 10Number of false-twisting (turns/meter) 3400 3400 Temperature of heater(C) I Length of heater (mm) 900 900 Tension of twisting (g) I3 28Tension of untwisting (g) 24 39 Number of true twist (tums/meter 0 0""TAiiLE? EX-6 EX-7 Number of filaments of Nylon-6:

Multi-filament adhered to polyurethane elastic thread (number/anoptional cross section of the covered elastic yarn) l2 0 Multi-filamentnot adhered to polyurethane elastic read (number/an optional crosssection of the covered elastic yarn) I2 24 Covering property (Percent):

Weight of 0.5g 89 0 Weight of 2.0g '83 0 CI:* Coefficient of recovery ofelasticity (percent).. 6] 63 Coefficient of elongation (percent) 162I702 Index of torque 7 r 7 Existence of the twisting mass produced by rubing motion None None CI value: Based on the rule ofJlS.

EX-S EX-9 EX-IO EX] 1 EX-IZ Materials:

Polyurethane thread (denier-filament) 70-l 70-] 70-1 70-1 70-1 Nylon-6multi filament (denier-filament) 70-24 70-24 70-24 70-24 70-24Conditions of processing:

Elongating degree of elastic thread (times) 3.6 3.6 3.6 3.6 3.6 Doublingtension of Nylon-6 multi-filament (g).. 0.2 0.2 2.0 2.0 2.0 Ratio oftension between an entry and an exit of the star-wheel type groovedguide 1.14 Existence of a grooved g u ide. Yes None None None NoneCoefficient of feeding of processing (percent) 1 1 I 1 Number ofrotations of false-twisting spindle 7 7* (rpm) 20X 10 20 X 10 20 X10 20X10" 20 X 10 Number of false-twisting (tums/meter)..... 3,300 3,3002,300 2,300 2,300 Temperature of heater (C) 195 195 I50 150 190 Lengthof heater (mm) 900 900 900 900 900 Tension of twisting (g) 16 '14 14 14Tension of untwisting (g)..... 32 32 v 28 28 28 Number of true twist(turns/meter)... 0 0 300 0 0 As is apparent from the foregoingdiscussion a starwheel type grooved pulley is used in both Exampleo 20and in Example 7 however, the covered elastic yarn in accordance withExample-6, in which the temperature of heat setting of false-twisting isthe same as that of conventional false twisting methods has a smallcovering property. Therefore, in order to obtain a covered elastic yarnhaving excellent covering property, it is preferable that a temperatureof the heat setting of false-twisting, as is in Example-6, is higherthan that of conventional false-twisting methods.

EXAMPLES 8,9, 10,11 AND 12 1. Examples 8 and 9 A polyurethaneelasticthread 70'denier-l filament elongated by a 3.6 times the originallength thereof and Nylon-6, 70 denier-24 filaments under 0.1g tensionwere associated with each other, and thereafter ther respectiveassociated filaments were supplied to apparatus of the type shown inFIG. 6 and FIG. 7 and treated under conditions as shown in items EX-8and EX-9 of Table-8. 40

The results as shown in items EX-8 and EX-9 of Table-9 were obtained.

As is apparent from the foregoing discussion, the

covering property of the covered elastic yarn of Example 8 produced withthe apparatus embodiment of FIG. 7 is better than that of the coveredelastic yarn of Example 9 produced the apparatus embodiment of FIG. 6.

2. Example 10 On the other hand, threads used in Examples8 and 5 9 weretreated by a conventional method.

The conventional method used (as taught in Japanese Patent PublicationNo.255l l/67) comprises a first step of associating said elastic threadwith said thermoplastic multi-filament thread, a second step ofpro-twisting said associated threads, a third. step of twisting saidthreads in the direction opposite to that of the original twist-heatsettingand'untwisting said threads in the same direction as that of theoriginal twist. I

Conditions of treatment of the present example are shown in item EX-9 ofTable-8 and the effects thereof are shown in item EX-9 of Table-9. As isapparent from the above result, the covered elastic yarn produced inaccordance with Example-l0 has practically no rubbing resistance andforms a twist-' ing mass in the longitudinal direction thereof directlyafter it was rubbed, because it is twisted slightly.

The covering property of said yarnof the present example has somewhatsimilar property to that of the yarn of the present invention.

The reason for said effect is that some of the original twist impartedby the pre-twisting process is retained after twisting-heatsetting-untwisting.

However, in said covered elastic yarn, the elastic thread and thethermoplastic multi-filament thread are not substantially twistless asin the present invention.

Furthermore, in the present example, the covered elastic yarns treatedwithout any pre-wisting process are not always'the same in coveringproperty as the above mentioned result as is apparent from the followingexamples (Examples 11 and 12).

3. Example 11 The covered elastic yarn of this example was obtained bythe method of Example 10', but without any pre-twisting.

In the covered elastic yarn of this example, the elastic thread andthermoplastic multi-filament were substantially twistless, but thecovering property thereof was very poor as is apparent from item EX-llof Table-9.

Furthermore, the covering properties of 38 (with a weight of 0.5g) and34 (with a weight of 2.0g) seem to indicate some degrees of coveringproperty, but

, as a matter of fact, the yarn obtained by this example is of almost nopractical value, because the portions covered therefor uncovered withsaid thermoplastic multi-filament were randomly distributed along thelongitudinal direction of said yarn.

4. Example 12 Furthermore, to make sure of the result reported inExample 11, the method of Example 11 was repeated, but at a heatsettingtemperature in the vicinity of Examples 8 and 9. As the result, acovering property of the covered elastic yarn of this example was moreexcellent than that of Examplefl 1,. but the covering property thereofwas not completely perfect, and the coefficient of recovery ofelasticity was lower than that of Examples 10 and l l.

TABLE 9 EX-8 EX-9 EX-lO EX-l l EX-l2 Number of filaments of Nylon-6:

Multi-filament adhered to polyurethane (numberlan optional cross sectionof the covered elastic yarn) 13 8 0 0 Multi-filament not adhered topolyurethane .elastic thread (number/an optional cross section of thecovered elastic yarn) 1 l 16 24 24 24 Covering property (percent):

Weight of0.5g 100 81 100 38 71.6 Weight of 2.0g 99 76 98.5 34 63.5 ClCoefficient of recov'erity of elasticity (percent). 62 59 6I 64 lCoefficient of elongation (percent) 167 163 159 I72 143 Index of torque9 9 l2 8 6 Existence of the twisting mass produced by ru ing motion 1.None None None None None *Cl value: It is based on the rule of .IIS.

elastic thread, the wrapping direction thereof being reversed atirregular intervals in the longitudinal direction of said elasticthreads, and

5. said thermoplastic multi-filament thread and said elastic threadbeing substantially twistless.

2 A covered elastic yarn according to claim 1,

wherein said filaments of said thermoplastic multifilament thread arepartially adhered to said elastic thread along the longitudinaldirection thereof.

3. A covered elastic yarn, according to claim 1, wherein said centrallydisposed elastic thread consists of a thermoplastic material.

4. A covered elastic yarn, according to claim 1, wherein said centrallydisposed elastic thread consists of a multi-filament yarn.

5. A covered elastic yarn, according to claim 1, wherein said centrallydisposed elastic thread consists of an essentially monofilament yarnformed by coalescing a thermoplastic multi-filament yarn.

6. A covered elastic yarn, according to claim 5, wherein said filamentsof said thermoplastic multifilament thread disposed about said elasticthread are partially adhered to said elastic thread along the lengththereof.

1. A covered elastic yarn comprising,
 1. two filament groups consistingof a thermoplastic multifilament thread and an elastic thread,
 2. saidelastic thread being larger in diameter than the filaments forming saidthermoplastic multi-filament,
 3. said elastic thread being positioned ina central portion of the filaments of said thermoplastic multi-filamentthread, said filaments being distributed about said central portion andclosely adjacent thereto,
 4. respective filaments of said thermoplasticmulti-filament thread being wrapped spirally around said elastic thread,the wrapping direction thereof being reversed at irregular intervals inthe longitudinal direction of said elastic threads, and
 5. saidthermoplastic multi-filament thread and said elastic thread beingsubstantially twistless. CM,2Ered elastic yarn according to claim 1,wherein said filaments of said thermoplastic multi-filament thread arepartially adhered to said elastic thread along the longitudinaldirection thereof.
 2. said elastic thread being larger in diameter thanthe filaments forming said thermoplastic multi-filament,
 3. said elasticthread being positioned in a central portion of the filaments of saidthermoplastic multi-filament thread, said filaments being distributedabout said central portion and closely adjacent thereto,
 3. A coveredelastic yarn, according to claim 1, wherein said centrally disposedelastic thread consists of a thermoplastic material.
 4. A coveredelastic yarn, according to claim 1, wherein said centrally disposedelastic thread consists of a multi-filament yarn.
 4. respectivefilaments of said thermoplastic multi-filament thread being wrappedspirally around said elastic thread, the wrapping direction thereofbeing reversed at irregular intervals in the longitudinal direction ofsaid elastic threads, and
 5. said thermoplastic multi-filament threadand said elastic thread being substantially twistless. 2 A coveredelastic yarn according to claim 1, wherein said filaments of saidthermoplastic multi-filament thread are partially adhered to saidelastic thread along the longitudinal direction thereof.
 5. A coveredelastic yarn, according to claim 1, wherein said centrally disposedelastic thread consists of an essentially monofilament yarn formed bycoalescing a thermoplastic multi-filament yarn.
 6. A covered elasticyarn, according to claim 5, wherein said filaments of said thermoplasticmulti-filament thread disposed about said elastic tHread are partiallyadhered to said elastic thread along the length thereof.